Consider the letter R in most English words: in words of at least three letters, do you think R is more likely to appear in the first position of a word or in the third position?

When Tversky and Kahneman asked this question to survey participants, a large majority answered that R appears more frequentlyin the first position. The correct answer is that more words in English feature R in the third spot. Why would people intuitively think differently?

It is easier, Tversky and Kahneman answered, to think of words that begin with R--and people use this ease of recall as a cue about frequency. The intuition goes something like: "Hmm...rabbit, road, race, rock, roll...it sure is easy to think of words where R comes first...card...care?...this one is harder. There must be more words where R comes first." This rule of thumb is known as the availability heuristic: we think what is more mentally available (i.e. easier to recall or imagine) is more likely.

A caveman would have a hard time imagining how a
computing machine would ever be built. That doesn't
change the likelihood it would happen.

In particular, people will often use the ease of imagining a scenario to judge how likely it is. For example, if you see a car accident, it becomes easier for you to imagine one, and you will have an increased estimate of the likelihood of getting in an accident.

In reality, though, the ease of remembering or imagining a scenario does not necessarily tell you how likely it is. So, for example, people heavily overestimate the number of deaths from tornadoes each year but underestimate the number of deaths from drowning each year, because we hear more on the news about tornadoes than drowning--it is more available.

Like all heuristics, this one can be useful in daily life, but it is just a best guess that can easily be wrong--especially when we are dealing with the nature of the universe, which is complex. Daily life simply doesn't give us a basis for imagining what happens over eons (i.e. evolution), or at the quantum level (i.e. quantum indeterminacy), or at the level of the astronomical (i.e. the big bang). Therefore, scientific explanations can often be true and well-evidenced, yet difficult to imagine and thus counterintuitive.

Religious intuitions often draw on what is easily imaginable. I.e., "I just can't imagine how all life could have evolved on its own without a Creator." A commenter once wrote on this blog:

Every facet of the universe is so unbelievably complex, that any single element within the whole sufficiently testifies to the handiwork of the Creator. If a magnificent work of art cannot be formed by merely spilling paint, certainly the entire world cannot have been fashioned by accident. For the logical mind, seemingly there is nothing more irrational than suggesting G-d not create the world.

This comment is largely based on the representativeness heuristic, which was previously discussed. Beyond that, though, the author's confidence comes from the difficulty of imagining any alternative. It is indeed difficult to imagine how something complex can come about without conscious design--but that doesn't actually make it unlikely! It is the availability heuristic that incorrectly transforms a difficulty of imagination into an intuition of probability, and a gut instinct into a false sense of logic.

Indeed, it takes work and careful reasoning--not simply imaginative impulse--to override intuition and figure out how each piece came to be. In the case of evolution, for example, one can read books that carefully map out each step, likeThe Blind Watchmaker. But some people stop before that; they just take the fact that something is hard to imagine and incorrectly use that difficulty as a cue that it is unlikely.

Philosopher Dan Dennett aptly writes that a failure of imagination should not be mistaken for an insight into necessity. The availability heuristic explains why.

2 comments:

I don't know, or more likely have simply forgotten, the chemical explanation of how crystals are formed. Isn't it amazing that the mere random motion of molecules should lead to the formation of such intricate and beautiful structures? Or should one say: It is quite impossible that the mere random motion of molecules could lead to such a thing; the formation of crystals must be guided by divine intervention! I think that the great majority of literate people would regard anyone who made such an "argument" (if what is hardly more than a bit of emotional exclamation can be dignified with that name) as having simply embarrassed himself. The person's ignorance of natural causes is no basis at all for inferring a supernatural cause--especially not when the ignorance could be remedied by spending a few minutes on Wikipedia. That last condition may not obtain when we raise questions about order in the cosmos überhaupt, but the supposed "argument" is just as lame.

I'd also suspect that the people you have in mind as "literate" have some experience with critical thinking as a mode of thought, and/or have some experience with how intuition can fail in the face of critical analysis.